Feb. 9 (UPI) -- Older and overweight adults exhale more respiratory droplets into the air compared to their younger, lighter-weight counterparts, potentially making them COVID-19 "superspreaders," a study published Tuesday by PNAS found.
Adults age 26 and younger and those with a body mass index, or BMI, below 22 were "low spreaders of [the] exhaled" respiratory droplets from the nose and mouth that transmit the coronavirus, the data showed.
Conversely, adults with a higher BMI, which measures body weight according to a person's height, exhaled more of these droplets, particularly as they aged.
The findings may help explain how some people become "superspreaders" of COVID-19 and pass the virus on to large numbers of people, the researchers said.
Thirty-five, or 18%, of the 194 participants in the study generated 80% of the exhaled respiratory droplets produced by the group as a whole, with older, heavier participants driving that spread.
"Most of the droplets we exhale from our airways during natural breathing are smaller in size than conventionally filtered by masks, [and] they vary greatly in number depending on whether we have a lung infection, and our age and [weight]," study co-author David A. Edwards told UPI.
"These findings suggest that the control of respiratory droplet generation might be an effective strategy for containing the pandemic independent of variant, or even pathogen form," said Edwards, a professor of biomedical engineering at Harvard University.
The study measured exhaled respiratory droplets produced by 194 healthy adults at two locations: essential workers at No Evil Foods in Asheville, N.C. and of students, staff and faculty at Grand Rapids Community College in Michigan.
The researchers also assessed similar breathing patterns in eight monkeys infected with COVID-19.
Monkeys with higher amounts of the coronavirus in their systems tended to exhale larger amounts of it in the respiratory droplets they produced, according to the researchers.
The amount of virus in the respiratory droplets they produced began to increase at three days post-infection and continued to rise until at least day seven, before declining by day 14.
"Superspreading of COVID 19 is likely not only environmental, but biological," Edwards said.
"Just as with other diseases, there are indicators, like glucose for diabetes, that reflect our health risk [for COVID-19 spread] and that we can personally control independent of the environment," he said.